Question: If $x \oplus y = x-5y$ and $x \triangleright y = xy+2x-y$, find $(4 \triangleright -5) \oplus 0$.
Solution: First, find $4 \triangleright -5$ $ 4 \triangleright -5 = (4)(-5)+(2)(4)-(-5)$ $ \hphantom{4 \triangleright -5} = -7$ Now, find $-7 \oplus 0$ $ -7 \oplus 0 = -7-(5)(0)$ $ \hphantom{-7 \oplus 0} = -7$.